ELECTRICITY, like heat, only in a different way, has also a certain omnipresent character.
Hardly any change can occur in the world without it being possible to demonstrate the
presence of electrical phenomena. If water evaporates, if a flame burns, if two different
metals, or two metals of different temperature, touch, or if iron touches a solution of
copper sulphate, and so on, electrical processes take place simultaneously with the more
apparent physical and chemical phenomena. The more exactly we investigate natural processes
of the most diverse nature, the more do we find evidence of electricity. In spite of its
omnipresence, in spite of the fact that for half a century electricity has become more and
more pressed into the industrial service of mankind, it remains precisely that form of motion
the nature of which is still enveloped in the greatest obscurity.

The discovery of the galvanic current is approximately 25 years younger than that of
oxygen and is at least as significant. for the theory of electricity as the latter discovery
was for chemistry. Yet what a difference obtains even to-day between the two fields ! In
chemistry, thanks especially to Dalton's discovery of
atomic weights, there is order,
relative certainty about what has been achieved, and systematic, almost planned, attack on
the territory still unconquered, comparable to the regular siege of a fortress. In the theory
of electricity there is a barren lumber of ancient, doubtful experiments, neither definitely
confirmed nor definitely refuted; , an uncertain fumbling in the dark, uncoordinated research
and experiment on the part of numerous isolated individuals, who attack the unknown territory
with their scattered forces like the attack of a swarm of nomadic horsemen. It must be
admitted, indeed, that in the sphere of electricity a discovery like that of Dalton, giving
the whole science a central point and a firm basis for research, is still to seek.[2] It is essentially this unsettled state of
the theory of electricity, which for the time being makes it impossible to establish a
comprehensive theory, that is responsible for the fact that a one-sided empiricism prevails
in this sphere, an empiricism which as far as possible itself forbids thought, and which
precisely for that reason not only thinks incorrectly but also is incapable of faithfully
pursuing the facts or even of reporting them faithfully, and which, therefore, becomes
transformed into the opposite of true empiricism.

If in general those natural scientists, who cannot say anything bad enough of the crazy
a priori speculations of the German philosophy of nature, are to be recommended to
read the theoretico-physical works of the empirical school, not only of the contemporary but
even of a much later period, this holds good quite especially for the theory of electricity.
Let us take a work of the year 1840: An Outline of the Sciences of Heat and
Electricity, by Thomas Thomson. Old Thomson was indeed an authority in his day ;
moreover he had already at his disposal a very considerable part of the work of
the greatest electrician so far - Faraday. Yet his book contains at least just as crazy things as the corresponding section of the much older Hegelian philosophy of nature. The description of
the electric spark, for instance, might have been translated directly from the corresponding
passage in Hegel. Both enumerate all the wonders that people sought to discover in the
electric spark, prior to knowledge of its real nature and manifold diversity, and which have
now been shown to be mainly special cases or errors.

Still better, Thomson recounts quite seriously on p. 446 Dessaigne's cock-and-bull stories,
such as that, with a rising barometer and falling thermometer, glass, resin, silk, etc.,
become negatively electrified on immersion in mercury, but positively if instead the
barometer is falling and the temperature rising ; that in summer gold and several other
metals become positive on warming and negative on cooling, but in winter the reverse; that
with a high barometer and northerly wind they are strongly electric, positive if the
temperature is rising and I negative if it is falling, etc.

So much for the treatment of the facts. As regards a priori speculation, Thomson
favours us with the following treatment of the electric spark, derived from no lesser person
than Faraday himself:

"The spark is a discharge ... or weakening of the polarised inductive state of many
dielectric particles by means of a peculiar action of a few of these particles occupying a
very small and limited space. Faraday assumes that the few particles situated where the
discharge occurs are not merely pushed apart, but assume a peculiar, highly exalted,
condition for the time, i.e. that they have thrown on them all the surrounding
forces in succession and are thus brought into a proportionate intensity of condition,
perhaps equal to that of chemically combining atoms; that they then discharge the powers, in
the same manner
as the atoms do theirs, in some way at present unknown to us and so the end
of the whole. The ultimate effect is exactly as if a metallic wire had been put into the
place of the discharging particles, and it does not seem impossible that the principles of
action in both cases may, hereafter, prove to be the same." [3]

I have, adds Thomson, given this explanation of Faraday's in his own words, because I do
not understand it clearly. This will certainly have been the experience of other persons
also, quite as much as when they read in Hegel that in the electric spark " the special
materiality of the charged body does not as yet enter into the process but is determined
within it only in an elementary and spiritual way," and that electricity is " the anger, the
effervescence, proper to the body," its "angry self " that " is exhibited by every body when
excited." (Philosophy of Nature, paragraph 324, addendum.) [4]

Yet the basic thought of both Hegel and Faraday is the same. Both oppose the idea that
electricity is not a state of matter but a special, distinct variety of matter. And since in
the spark electricity is apparently exhibited as independent, free from any foreign material
substratum, separated out and yet perceptible to the senses, they arrive at the necessity,
in the state of science at the time, of having to conceive of the spark as a transient phenomenal
form of a " force " momentarily freed from all matter. For us, of course, the riddle is solved,
since we know that on the spark discharge between metal electrodes real "metallic particles" leap across, and hence in actual fact " the special materiality of the charged body enters
into the process."

As is well known, electricity and magnetism, like heat and light, were at first regarded
as special imponderable substances. As far as electricity is concerned,
it is well known that
the view soon developed that there are two opposing substances, two " fluids," one positive
and one negative, which in the normal state neutralise each other, until they are forced
apart by a so-called " electric force of separation." It is then possible to charge two
bodies, one with positive, the other with negative electricity; on uniting them by a third
conducting body equalisation occurs, either suddenly or by means of a lasting current,
according to circumstances. The sudden equalisation appeared very simple and comprehensible,
but the current offered difficulties. The simplest hypothesis, that the current in every case
is a movement of either purely positive or purely negative electricity, was opposed by
Fechner, and in more detail by Weber, with the view that in every circuit two equal currents
of positive and negative electricity flow in opposite directions in channels lying side by
side between the ponderable molecules of the bodies.[5] Weber's detailed mathematical working out of this
theory finally arrives at the result that a function, of no interest to us here, is
multiplied by a magnitude l/r, the latter signifying "the ratio . . . of the
unit of electricity to the milligram." (Wiedemann, Lehre vom Galvanismus, etc.
[Theory of Galvanism, etc.], 2nd edition, III, p. 569). The ratio to a measure of
weight can naturally only be a weight ratio. Hence one-side empiricism had already to such an
extent forgotten the practice of thought in calculating that here it even makes the
imponderable electricity ponderable and introduces its weight into the mathematical
calculation.

The formula derived by Weber sufficed only within certain limits, and Helmholtz, in
particular, only a few years ago calculated results that come into conflict
with the
principle of the conservation of energy. In opposition to Weber's hypothesis of the double
current flowing in opposite directions, C. Naumann in 1871 put forward the other hypothesis
that in the current only one of the two electricities, for instance the positive, moves,
while the other negative one remains firmly bound up with the mass of the body. On this
Wiedemann includes the remark: " This hypothesis could be linked up with that of Weber if to
Weber's supposed double current of electric masses ±½e flowing in opposite
directions, there were added a further current of neutral electricity, externally inactive,
which carried with it amounts of electricity ±½e in the direction of the positive
current." (III, p. 577.)

This statement is once again characteristic of one-sided empiricism. In order to bring
about the flow of electricity at all, it is decomposed into positive and negative. All
attempts, however, to explain the current with these two substances, meet with difficulties;
both the assumption that only one of them is present in the current and that the two of them
flow in opposite directions simultaneously, and finally, the third assumption also that one
flows and the other is at rest. If we adopt this last assumption how are we to explain the
inexplicable idea that negative electricity, which is mobile enough in the electrostatic
machine and the Leyden jar, in the current is firmly united with the mass of the body? Quite
simply. Besides the positive current +e, flowing through the wire to the right, and
the negative current, -e, flowing to the left, we make yet another current, this
time of neutral electricity, ±½e, flow to the right. First we assume that the two
electricities, to be able to flow at all, must be separated from one another ; and then, in
order to explain the phenomena that occur on the flow of the separated electricities, we
assume that they can also flow unseparated. First
we make a supposition to explain a
particular phenomenon, and at the first difficulty encountered we make a second supposition
which directly negates the first one. What must be the sort of philosophy that these
gentlemen have the right to complain of?

However, alongside this view of the material nature of electricity, there soon appeared a
second view, according to which it is to be regarded as a mere state of the body, a " force "
or, as we would say to-day, a special form of motion. We saw above that Hegel, and later
Faraday, adhered to this view. After the discovery of the mechanical equivalent of heat had
finally disposed of the idea of a special " heat stuff," and heat was shown to be a molecular
motion, the next step was to treat electricity also according to the new method and to
attempt to determine its mechanical equivalent. This attempt was fully successful.
Particularly owing to the experiments of Joule, Favre, and Raoult, not only was the
mechanical and thermal equivalent of the so-called " electromotive force " of the galvanic
current established, but also its complete equivalence with the energy liberated by chemical
processes in the exciting cell or used up in the decomposition cell. This made the assumption
that electricity is a special material fluid more and more untenable.

The analogy, however, between heat and electricity was not perfect. The galvanic currents
still differed in very essential respects from the conduction of heat. It was still not
possible to say what it was that moved in the electrically affected bodies. The
assumption of a mere molecular vibration as in the case of heat seemed insufficient. In view
of the enormous velocity of motion of electricity, even exceeding that of light,[6] it remained difficult to overcome the view that
here some
material substance is in motion between the molecules of the body.

Here the most recent theories put forward by Clerk Maxwell (1864), Hankel (1865), Reynard
(1870), and Edlund (1872) are in complete agreement with the assumption already advanced in
1846, first of all as a suggestion by Faraday, that electricity is a movement of the elastic
medium permeating the whole of space and hence all bodies as well, the discrete particles of
which medium repel one another according to the law of the inverse square of the distance. In
other words, it is a motion of ether particles, and the molecules of the body take part in
this motion. As to the manner of this motion, the various theories are divergent; those of
Maxwell, Hankel, and Reynard, taking as their basis modern investigations of vortex motion,
explain it in various ways from vortices, so that the vortex of old Descartes also once more
comes into favour in an increasing number of new fields. We refrain from going more closely
into the details of these theories. They differ strongly from one another and they will
certainly still experience many transformations. But a decisive advance appears to lie in
their common basic conception: that electricity is a motion of the particles of the
luminiferous ether that penetrates all ponderable matter, this motion reacting on the
molecules of the body. This conception reconciles the two earlier ones. According to it, it
is true that in electrical phenomena it is something substantial that moves, something
different from ponderable matter. But this substance is not electricity itself, which in fact
proves rather to be a form of motion, although not a form of the immediate direct motion of
ponderable matter. While, on the one hand, the ether theory shows a way of getting over the
primitive clumsy idea of two opposed electrical fluids, on the other hand it gives a prospect
of
explaining what the real, substantial substratum of electrical motion is,
what sort of a thing it is whose motion produces electrical phenomena .[7]

The ether theory has already had one decisive success. As is well known, there is
at least one point where electricity directly alters the motion of light: it rotates the
latter's plane of polarisation. On the basis of his theory mentioned above, Clerk Maxwell
calculates that the electric specific inductive capacity of a body is equal to the square of
its index of refraction. Boltzmann has investigated dielectric coefficients of various
nonconductors and he found that in sulphur, rosin, and paraffin, the square roots of these
coefficients were respectively equal to their indices of refraction. The highest deviation
- in sulphur - amounted to only 4 per cent. Consequently, the Maxwellian ether theory in this
particular has hereby been experimentally confirmed.[8]

It will, however, require a lengthy period and cost much labour before new series of
experiments will have extracted a firm kernel from these mutually contradictory hypotheses.
Until then, or until the ether theory, too, is perhaps supplanted by an entirely new one, the
theory of electricity finds itself in the uncomfortable position of having to employ a mode
of expression which it itself admits to be false. Its whole terminology is still based on the
idea of two electric fluids. It still speaks quite unashamedly of " electric masses flowing
in the bodies," of " a division of electricities in every molecule," etc. This is a
misfortune which for the most part, as already said, follows
inevitably from the present
transitional state of science, but which also, with the one-sided empiricism particularly
prevalent in this branch of investigation, contributes not a little to preserving the
existing confusion of thought.

The opposition between so-called static or frictional electricity and dynamic electricity
or galvanism can now be regarded as bridged over, since we have learned to produce constant
currents by means of the electric machine and, conversely, by means of the galvanic current
to produce so-called static electricity, to charge Leyden jars, etc. We shall not here touch
on the subform of static electricity, nor likewise on magnetism, which is now recognised to
be also a sub-form of electricity. The theoretical explanation of the phenomena belonging
here will under all circumstances have to be sought in the theory of the galvanic current,
and consequently we shall keep mainly to this.

A constant current can be produced in many different ways. Mechanical mass motion produces
directly, by friction, in the first place only static electricity, and a constant
current only with great dissipation of energy. For the major part, at least, to become
transformed into electric motion, the intervention of magnetism is required, as in the well-
known magneto-electric machines[9] of
Gramme, Siemens, and others. Heat can be converted directly into current electricity, as
especially occurs at the junction of two different metals. The energy set free by chemical
action, which under ordinary circumstances appears in the form of heat, is converted under
appropriate conditions into electric motion. Conversely, the latter form of motion, as soon
as the requisite conditions are present, passes into any other form of motion: into mass
motion, to a very small extent directly into electro-dynamic attractions and repulsions; to a
large extent, however, by the intervention
of magnetism in the electro-magnetic machine; into
heat - throughout a closed circuit, unless other changes are brought about; into chemical
energy - in decomposition cells and voltameters introduced into the circuit, where the current
dissociates compounds that are attacked in vain by other means.

All these transformations are governed by the basic law of the quantitative equivalence of
motion through all its changes of form. Or, as Wiedemann expresses it: "By the law of
conservation of force the mechanical work exerted in any way for the production of the
current must be equivalent to the work exerted in producing all the effects of the current."
The conversion of mass motion or heat into electricity[10] offers us no difficulties here; it has been shown
that the so- called "electromotive force"[11] in the first case is equal to the work expended on
that motion, and in the second case it is " at every junction of the thermopile directly
proportional to its absolute temperature " (Wiedemann, III, p. 482), i.e. to the
quantity of heat present at every junction measured in absolute units. The same law has in
fact been proved valid also for electricity produced from chemical energy. But here the
matter seems to be not so simple, at least for the theory now current. Let us, therefore, go
into this somewhat more deeply.

One of the most beautiful series of experiments on the transformations of form of motion
as a result of the action of a galvanic cell is that of Favre (1857-58). He put a Smee cell
of five elements in a calorimeter;
in a second calorimeter he put a small electro-magnetic
motor, with the main axle and driving wheel projecting so as to be available for any kind of
coupling. Each production in the cell of one gram of hydrogen, or solution of 32·6 grams of
zinc (the old chemical equivalent of zinc, equal to half the now accepted atomic weight 65·2,
and expressed in grams), gave the following results:

A. The cell enclosed in the calorimeter, excluding the motor: heat
production 18,682 or 18,674 units of heat.

B. Cell and motor linked in the circuit, but the motor prevented from
moving: heat in the cell 16,448, in the motor 2,219, together 18,667 units of heat.

C. As B, but the motor in motion without however lifting a
weight: heat in the cell 13,888, in the motor 4,769, together 18,657 units of heat.

D. As C, but the motor raises a weight and so performs
mechanical work==131,24 kilogram-metres: heat in the cell 15,427, in the motor 2,947, total
18,374 units of heat; loss in contrast to the above 18,682 equals 308 units of heat. But the
mechanical work performed amounting to 131,24 kilogram-metres, multiplied by 1,000 (in order
to bring the kilograms into line with the grams of the chemical results) and divided by the
mechanical equivalent of heat== 423,5 kilogram-metres, gives 309 units of heat, hence exactly
the loss mentioned above as the heat equivalent of the mechanical work performed.

The equivalence of motion in all its transformations is, therefore, strikingly proved for
electric motion also, within the limits of unavoidable error. And it is likewise proved that
the " electromotive force " of the galvanic battery is nothing but chemical energy converted
into electricity, and the battery itself nothing but an apparatus that converts chemical
energy on its
liberation into electricity, just as a steam engine trans forms the heat
supplied to it into mechanical motion, without in either case the converting apparatus
supplying further energy on its own account.

A difficulty arises here, however, in relation to the traditional mode of conception. The
latter ascribes an "electric force of separation." to the battery in virtue of the
conditions of contact present in it between the fluids and metals, which force is
proportional to the electromotive force and therefore for a given battery represents a
definite quantity of energy. What then is the relation of this electric force of separation,
which according to the traditional mode of conception of the battery as such is inherently a
source of energy even without chemical action, to the energy set free by chemical action?
And if it is a source of energy independent of the latter, whence comes the energy furnished
by it?

This question in a more or less unclear form constitutes the point of dispute between the
contact theory founded by Volta and the chemical theory of the galvanic current that arose
immediately afterwards.

The contact theory explained the current from the electric stresses arising in the battery
on contact of the metals with one or more of the liquids, or even merely on contact of the
liquids themselves, and from their neutralisation or that of the opposing electricities thus
generated in the circuit. The pure contact theory regarded any chemical changes that might
thereby occur as quite secondary. On the other hand, as early as 1805, Ritter maintained that
a current could only be formed if the excitants reacted chemically even before
closing the circuit. In general this older chemical theory is summarised by Wiedemann (I, p.
284) to the effect that according to it so-called contact electricity "makes its appearance
only if at the same time there comes into play a real chemical action of the
bodies in contact, or at any rate a disturbance of the chemical equilibrium, even if not
directly bound up with chemical processes, a `tendency towards chemical action' between the
bodies in contact."

It is seen that both sides put the question of the source of energy of the current only
indirectly, as indeed could hardly be otherwise at the time. Volta and his successors found
it quite in order that the mere contact of heterogeneous bodies should produce a constant
current, and consequently be able to perform definite work without equivalent return. Ritter
and his supporters are just as little clear how the chemical action makes the battery capable
of producing the current and its performance of work. But if this point has long ago been
cleared up for chemical theory by Joule, Favre, Raoult, and others, the opposite is the case
for the contact theory. In so far as it has persisted, it remains essentially at the point
where it started. Notions belonging to a period long outlived, a period when one had to be
satisfied to ascribe a particular effect to the first available apparent cause that showed
itself on the surface, regardless of whether motion was thereby made to arise out of nothing-
notions that directly contradict the principle of the conservation of energy-thus continue to
exist in the theory of electricity of to-day. And if the objectionable aspects of these ideas
are shorn off, weakened, watered down, castrated, glossed over, this does not improve matters
at all: the confusion is bound to become only so much the worse.

As we have seen, even the older chemical theory of the current declares the contact
relations of the battery to be absolutely indispensable for the formation of the current: it
maintains only that these contacts can never achieve a constant current without simultaneous
chemical action. And even to-day it is still taken as a matter of course that the contact
arrangements of the battery
provide precisely the apparatus by means of which liberated chemical energy is transformed
into electricity, and that it depends essentially on these contact arrangements whether and
how much chemical energy actually passes into electric motion.

Wiedemann, as a one-sided empiricist, seeks to save what can be saved of the old contact
theory. Let us follow what he has to say. He declares (I, p. 799):

" In contrast to what was formerly believed, the effect of contact of
chemically indifferent bodies, e.g. of metals, is neither indispensable for the
theory of the pile, nor proved by the facts that Ohm derived his law from it, a
law that can be derived without this assumption, and that Fechner, who confirmed
this law experimentally, likewise defended the contact theory. Nevertheless, the excitation
of electricity by metallic contact, according to the experiments now available at
least, is not to be denied, even though the quantitative results obtainable in this respect
may always be tainted with an inevitable uncertainty owing to the impossibility of keeping
absolutely clean the surfaces of the bodies in contact."

It is seen that the contact theory has become very modest. It concedes that it is not at
all indispensable for explaining the current, and neither proved theoretically by Ohm nor
experimentally by Fechner. It even concedes then that the so-called fundamental experiments,
on which alone it can still rest, can never furnish other than uncertain results in a
quantitative respect, and finally it asks us merely to recognise that in general it is by
contact - although only of metals! - that electric motion occurs.

If the contact theory remained content with this, there would not be a word to say against
it. It will certainly be granted that on the contact of two metals electrical phenomena
occur, in virtue of which a preparation of a frog's leg can be made to twitch, an
electroscope
charged, and other movements brought about. The only question that arises in the first place
is: whence comes the energy required for this?

To answer this question, we shall, according to Wiedemann (I, p.14)

"adduce more or less the following considerations: if the heterogeneous metal
plates A and B are brought within a close distance of each
other, they attract each other in consequence of the forces of adhesion. On mutual contact
they lose the vis viva[12]
of motion imparted to them by this attraction. (If we assume that the molecules of the metals
are in a state of permanent vibration, it could also happen that, if on contact of
the heterogeneous metals the molecules not vibrating simultaneously come into contact, an
alteration of their vibration is thereby brought about with loss of vis viva.) The
lost vis viva is to a large extent converted into heat. A small
portion of it, however, is expended in bringing about a different distribution of the
electricities previously unseparated. As we have already mentioned above, the bodies brought
together become charged with equal quantities of positive and negative electricity,
possibly as the result of an unequal attraction for the two
electricities."

The modesty of the contact theory becomes greater and greater. At first it is admitted
that the powerful electric force of separation, which has later such a gigantic work to
perform, in itself possesses no energy of its own, and that it cannot function if energy is
not supplied to it from outside. And then it has allotted to it a more than diminutive source
of energy, the vis viva of adhesion, which only comes into play at scarcely
measurable distances and which allows the bodies to travel a scarcely measurable length. But
it does not matter: it indisputably exists and equally undeniably
vanishes on contact. But even this minute source still furnishes too much energy for our
purpose: a large part is converted into heat and only a small portion
serves to evoke the electric force of separation. Now, although it is well known that cases
enough occur in nature where extremely minute impulses bring about extremely powerful
effects, Wiedemann himself seems to feel that his hardly trickling source of energy can with
difficulty suffice here, and he seeks a possible second source in the assumption of an
interference of the molecular vibrations of the two metals at the surfaces of contact. Apart
from other difficulties encountered here, Grove and Gassiot have shown that for exciting
electricity actual contact is not at all indispensable, as Wiedemann himself tells us on the
previous page. In short, the more we examine it the more does the source of energy for the
electric force of separation dwindle to nothing.

Yet up to now we hardly know of any other source for the excitation of electricity on
metallic contact. According to Naumann (Allg. u. phys. Chemie [General and
Physical Chemistry], Heidelberg, 1877, p. 675), "the contact-electromotive forces
convert heat into electricity"; he finds "the assumption natural that the ability of these
forces to produce electric motion depends on the quantity of heat present, or, in other
words, that it is a function of the temperature," as has also been proved experimentally by
Le Roux. Here too we find ourselves groping in the dark. The law of the voltaic series of
metals forbids us to have recourse to the chemical processes that to a small extent are
continually taking place at the contact surfaces, which are always covered by a thin layer of
air and impure water, a layer as good as inseparable as far as we are concerned. An
electrolyte should produce a constant current in the circuit, but the electricity of mere
metallic
contact, on the contrary, disappears on closing the circuit. And here we come to the real
point: whether, and in what manner, the production of a constant current on the contact of
chemically indifferent bodies is made possible by this "electric force of separation," which
Wiedemann himself first of all restricted to metals, declaring it incapable of functioning
without energy being supplied from outside, and then referred exclusively to a truly
microscopical source of energy.

The voltaic series arranges the metals in such a sequence that each one behaves as
electro-negative in relation to the preceding one and as electro-positive in relation to the
one that follows it. Hence if we arrange a series of pieces of metal in this order,
e.g. zinc, tin, iron, copper, platinum, we shall be able to obtain differences of
electric potential at the two ends. If, however, we arrange the series of metals to form a
circuit so that the zinc and platinum are in contact, the electric stress is at once
neutralised and disappears. "Therefore the production of a constant current of electricity is
not possible in a closed circuit of bodies belonging to the voltaic series." Wiedemann
further supports this statement by the following theoretical consideration:

"In fact, if a constant electric current were to make its appearance in the
circuit, it would produce heat in the metallic conductors themselves, and this heating could
at the most be counterbalanced by cooling at the metallic junctions. In any case it would
give rise to an uneven distribution of heat; moreover an electro-magnetic motor could be
driven continuously by the current without any sort of supply from outside, and thus work
would be performed, which is impossible, since on firmly joining the metals, for instance by
soldering, no further changes to compensate for this work could take place even at the
contact surfaces."

And not content with the theoretical and experimental proof that the contact electricity of
metals by itself cannot produce any current, we shall see too that Wiedemann finds himself
compelled to put forward a special hypothesis to abolish its activity even where it might
perhaps make itself evident in the current.

Let us, therefore, try another way of passing from contact electricity to the current. Let
us imagine, with Wiedemann, "two metals, such as a zinc rod and a copper rod, soldered
together at one end, but with their free ends connected by a third body that does
not act electromotively in relation to the two metals, but only conducts the
opposing electricities collected on its surfaces, so that they are neutralised in it. Then
the electric force of separation would always restore the previous difference of potential,
thus a constant electric current would make its appearance in the circuit, a current that
would be able to perform work without any compensation, which again is
impossible. - Accordingly, there cannot be a body which only conducts electricity without
electromotive activity in relation to the other bodies." We are no better off than before:
the impossibility of creating motion again bars the way. By the contact of chemically
indifferent bodies, hence by contact electricity as such, we shall never produce a current.

Let us therefore go back again and try a third way pointed out by Wiedemann:

"Finally, if we immerse a zinc plate and a copper plate in a liquid that contains a so-
called binary compound,[13]
which therefore can be decomposed into two chemically distinct constituents that completely
saturate one another, e.g. dilute hydrochloric acid (H+Cl), etc., then according to
paragraph 27 the zinc becomes negatively charged and the copper
positively. On joining the metals, these electricities neutralise one another through the
place of contact, through which, therefore, a current of positive electricity flows
from the copper to the zinc. Moreover, since the electric force of separation making its
appearance on the contact of these two metals carries away the positive electricity in
the same direction, the effects of the electric forces of separation are not
abolished as in a closed metallic circuit. Hence there arises a constant current of
positive electricity, flowing in the closed circuit through the copper-zinc junction in
the direction of the latter, and through the liquid from the zinc to the copper. We shall
return in a moment (paragraph 34, et seq.) to the question how far the individual
electric forces of separation present in the enclosed circuit really participate in
the formation of the current. - A combination of conductors providing such a 'galvanic
current' we term a galvanic element, or also a galvanic battery." (I, p. 45.)

Thus the miracle has been accomplished. By the mere electric contact force of separation,
which, according to Wiedemann himself, cannot be effective without energy being supplied from
outside, a constant current. has been produced. And if we were offered nothing more for its
explanation than the above passage from Wiedemann, it would indeed be an absolute miracle.
What have we learned here about the process?

1. If zinc and copper are immersed in a liquid containing a so-called
binary compound, then, according to paragraph 27, the zinc becomes negatively
charged and the copper positively charged. But in the whole of paragraph 27 there is no word
of any binary compound. It describes only a simple voltaic element of a zinc plate and copper
plate, with a piece of cloth moistened by an acid liquid interposed between them,
and then investigates, without mentioning any chemical processes, the resulting static-
electric charges of the two metals.

Hence, the so-called binary compound has been smuggled in here by the back-door.

2. What this binary compound is doing here remains completely mysterious.
The circumstance that it "can be decomposed into two chemical constituents that
fully saturate each other" (fully saturate each other after they have been decomposed?!)
could at most teach us something new if it were actually to decompose. But we are
not told a word about that, hence for the time being we have to assume that it does
not decompose, e.g. in the case of paraffin.

3. When the zinc in the liquid has been negatively charged, and the
copper positively charged, we bring them into contact (outside the liquid). At once "these
electricities neutralise one another through the place of contact, through which therefore a
current of positive electricity flows from the copper to the zinc." Again, we do not
learn why only a current of "positive" electricity flows in the one direction, and not also a
current of "negative", electricity in the opposite direction. We do not learn at all what
becomes of the negative electricity, which, hitherto, was just as necessary as the positive;
the effect of the electric force of separation consisted precisely in setting them free to
oppose one another. Now it has been suddenly suppressed, as it were eliminated, and it is
made to appear as if there exists only positive electricity.

But then again, on p. 51, the precise opposite is said, for here "the electricities
unite in one current"; consequently both negative and positive flow in it! Who will
rescue us from this confusion?

4. "Moreover, since the electric force of separation making its
appearance on the contact with these two metals carries away the positive
electricity in the same direction, the effects of the electric forces of separation
are not abolished as in a closed metallic circuit. Hence,
there arises a constant current," etc. - This is a bit thick. For as we shall see a few pages
later (p. 52), Wiedemann proves to us that on the "formation of a constant current ... the
electric force of separation at the place of contact of the metals ... must be
inactive, that not only does a current occur even when this force, instead of carrying
away the positive electricity in the same direction, acts in opposition to the direction of
the current, but that in this case too it is not compensated by a definite share of the force
of separation of the battery and, hence, once again is inactive." Consequently, how can
Wiedemann on p. 45 make an electric force of separation participate as a necessary factor in
the formation of the current when on p. 52 he puts it out of action for the duration of the
current, and that, moreover, by a hypothesis erected specially for this purpose?

5. " Hence there arises a constant current of positive
electricity, flowing in the closed circuit from the copper through its place of contact with
the zinc, in the direction of the latter, and through the liquid from the zinc to the
copper." - But in the case of such a constant electric current, "heat would be produced by it
in the conductors themselves," and also it would be possible for "an electro-magnetic motor
to be driven by it and thus work performed," which, however, is impossible without supply of
energy. Since Wiedemann up to now has not breathed a syllable as to whether such a supply of
energy occurs, or whence it comes, the constant current so far remains just as much an
impossibility as in both the previously investigated cases.

No one feels this more than Wiedemann himself. So he finds it desirable to hurry as
quickly as possible over the many ticklish points of this remarkable explanation of current
formation, and instead to entertain the reader throughout several pages with all kinds of
elementary
anecdotes about the thermal, chemical, magnetic, and physiological effects of this still
mysterious current, in the course of which by way of exception he even adopts a quite popular
tone. Then he suddenly continues (p. 49):

"We have now to investigate in what way the electric forces of separation are active in a
closed circuit of two metals and a liquid, e.g. zinc, copper, and hydrochloric
acid."

" We know that when the current traverses the liquid the constituents of the
binary compound (HCl) contained in it become separated in such a manner that one constituent
(H) is set free on the copper, and an equivalent amount of the other (Cl) on the
zinc, whereby the latter constituent combines with an equivalent amount of zinc to
form ZnCl."

We know! If we know this, we certainly do not know it from Wiedemann who, as we
have seen, so far has not breathed a syllable about this process. Further, if we do
know anything of this process, it is that it cannot proceed in the way described by
Wiedemann.

On the formation of a molecule of HCl from hydrogen and chlorine, an amount of energy
==22,000 units of heat is liberated (Julius Thomsen). Therefore, to break away the chlorine
from its combination with hydrogen, the same quantity of energy must be supplied from outside
for each molecule of HCl. Where does the battery derive this energy? Wiedemann's description
does not tell us, so let us look for ourselves.

When chlorine combines with zinc to form zinc chloride a considerably greater quantity of
energy is liberated than is necessary to separate chlorine from hydrogen;
(Zn,Cl2) develops 97,210 and 2(H,Cl) 44,000 units of heat (Julius
Thomsen). With that the process in the battery becomes comprehensible. Hence it is not, as
Wiedemann relates, that hydrogen without
more ado is liberated from the copper, and chlorine from the zinc, "whereby" then
subsequently and accidentally the zinc and chlorine enter into combination. On the contrary,
the union of the zinc with the chlorine is the essential, basic condition for the whole
process, and as long as this does not take place, one would wait in vain for hydrogen on the
copper.

The excess of energy liberated on formation of a molecule of
ZnCl2 over that expended on liberating two atoms of H from two
molecules of HCl, is converted in the battery into electric motion and provides the entire
"electromotive force" that makes its appearance in the current circuit. Hence it is not a
mysterious "electric force of separation" that tears asunder hydrogen and chlorine without
any demonstrable source of energy, it is the total chemical process taking place in the
battery that endows all the "electric forces of separation" and "electromotive forces" of the
circuit with the energy necessary for their existence.

For the time being, therefore, we put on record that Wiedemann's second
explanation of the current gives us just as little assistance as his first one, and let us
proceed further with the text:

"This process proves that the behaviour of the binary substance between the metals does
not consist merely in a simple predominant attraction of its entire mass for one electricity
or the other, as in the case of metals, but that in addition a special action of its
constituents is exhibited. Since the constituent Cl is given off where the current of
positive electricity enters the fluid, and the constituent H where the negative electricity
enters, we assume that each equivalent of chlorine in the compound HCl is charged
with a definite amount of negative electricity determining its attraction by the entering
positive electricity. It is the electro-negative constituent of the
compound. Similarly the equivalent H must be charged with positive electricity and so
represent the electro-positive constituent of the compound. These charges could be
produced on the combination of H and Cl in just the same way as on the contact of zinc and
copper. Since the compound HCl as such is non-electric, we must assume accordingly
that in it the atoms of the positive and negative constituents contain equal
quantities of positive and negative electricity.

If now a zinc plate and a copper plate are dipped in dilute hydrochloric acid, we can
suppose that the zinc has a stronger attraction towards the electro-negative constituent
(Cl) than towards the electropositive one (H). Consequently, the molecules of hydrochloric
acid in contact with the zinc would dispose themselves so that their electro-
negative constituents are turned towards the zinc, and their electro-positive constituents
towards the copper. Owing to the constituents when so arranged exerting their electrical
attraction on the constituents of the next molecules of HCl, the whole series of molecules
between the zinc and copper plates becomes arranged as in Fig. 10:

- Zinc

Copper +

-

+

-

+

-

+

-

+

-

+

Cl

H

Cl

H

Cl

H

Cl

H

Cl

H

If the second metal acts on the positive hydrogen as the zinc does on the negative chlorine,
it would help to promote the arrangement. If it acted in the opposite manner, only more
weakly, at least the direction would remain unaltered.

By the influence exerted by the negative electricity of the electro-negative constituent
Cl adjacent to the zinc, the electricity would be so distributed in the zinc that
places on it which are close to the Cl of the immediately adjacent atom of acid would become
charged positively, those farther away negatively.

Similarly, negative electricity would accumulate in the .copper next to the electro-positive
constituent (H) of the adjacent atom of hydrochloric acid, and the positive electricity would
be driven to the more remote parts.

Next, the positive electricity in the zinc would combine with the
negative electricity of the immediately adjacent atom of Cl, and the latter itself with the
zinc, to form non-electric ZnCl2. The electro-positive atom H,
which was previously combined with this atom of Cl, would unite with the atom of Cl
turned towards it belonging to the second atom of HCl, with simultaneous combination of the
electricities contained in these atoms; similarly, the H of the second atom of HCl would
combine with the Cl of the third atom, and so on, until finally an atom of H
would be set free on the copper, the positive electricity of which would unite with
the distributed negative electricity of the copper, so that it escapes in a non-electrified
condition." This process would "repeat itself until the repulsive action of the electricities
accumulated in the metal plates on the electricities of the hydrochloric acid constituents
turned towards them balances the chemical attraction of the latter by the metals. If,
however, the metal plates are joined by a conductor, the free electricities of the metal
plates unite with one another and the above-mentioned processes can recommence. In this
way a constant current of electricity comes into being. - It is evident that in the
course of it a continual loss of vis viva occurs, owing to the constituents of the
binary compound on their migration to the metals moving to the latter with a definite
velocity and then coming to rest, either with formation of a compound
(ZnCl2) or by escaping in the free state (H). (Note
[by Wiedemann]: Since the gain in vis viva on separation of the
constituents Cl and H ... is compensated by the vis viva lost on the union of
these constituents with the constituents of the adjacent atoms, the influence of this process
can be neglected.) This loss of vis viva is equivalent to the quantity of heat
which is set free in the visibly occurring chemical process, essentially, therefore, that
produced on the solution of an equivalent of zinc in the dilute acid. This value must be the
same as that of the work expended on separating the electricities. If, therefore, the
electricities unite to form a current, then, during the solution of an equivalent of zinc and
the giving off of an equivalent of hydrogen from the liquid, there must make its appearance
in the whole circuit, whether in the form of heat or in the form of external performance of
work, an amount of work that is likewise equivalent to the development of heat corresponding
to this chemical process."

"Let us assume - could - we must assume - we can suppose - would be distributed - would become
charged," etc., etc. Sheer conjecture and subjunctives from which only three actual
indicatives can be definitely extracted: firstly, that the combination of the zinc with the
chlorine is now pronounced to be the condition for the liberation of hydrogen;
secondly, as we now learn right at the end and as it were incidentally, that the energy
herewith liberated is the source, and indeed the exclusive source, of all energy required for
formation of the current; and thirdly, that this explanation of the current formation is as
directly in contradiction to both those previously given as the latter are themselves
mutually contradictory.

Further it is said:

"For the formation of a constant current, therefore, there is active wholly and solely the
electric force of separation which is derived from the unequal attraction and polarisation of
the atoms of the binary compound in the exciting liquid of the battery by the metal
electrodes; at the place of contact of the metals, at which no further mechanical changes can
occur, the electric force of separation must on the other
hand be inactive. That this force, if by chance it counteracts the
electromotive excitation of the metals by the liquid (as on immersion of zinc and lead in
potassium cyanide solution), is not compensated by a definite share of the force of
separation at the place of contact, is proved by the above-mentioned complete proportionality
of the total electric force of separation (and electromotive force) in the circuit, with the
abovementioned heat equivalent of the chemical process. Hence it must be neutralised in
another way. This would most simply occur on the assumption that on contact of the exciting
liquid with the metals the electromotive force is produced in a double manner; on the one
hand by an unequally strong attraction of the mass of the liquid as a whole towards
one or the other electricity, on the other hand by the unequal attraction of the metals
towards the constituents of the liquid charged with opposite electricities. ...
Owing to the former unequal (mass) attraction towards the electricities, the liquids would
fully conform to the law of the voltaic series of metals, and in a closed circuit ...
complete neutralisation to zero of the electric forces of separation (and electromotive
forces) take place; the second (chemical) action ... on the other hand would be
provided solely by the electric force of separation necessary for formation of the
current and the corresponding electromotive force." (I, pp. 52-3.)

Herewith the last relics of the contact theory are now happily eliminated from formation
of the current, and simultaneously also the last relics of Wiedemann's first explanation of
current formation given on p. 45. It is finally conceded without reservation that the
galvanic battery is a simple apparatus for converting liberated chemical energy into electric
motion, into so-called electric force of separation and electromotive force, in exactly the
same way as the steam engine is an apparatus for converting heat energy into mechanical
motion. In the one case, as in the other, the apparatus provides only the conditions for
liberation and further transformation of the energy, but supplies no energy on its own
account. This once established, it remains for us now to make a closer examination of this
third version of Wiedemann's explanation of the current.

How are the energy transformations in the circuit of the battery represented here?

It is evident, he says, that in the battery

"a continual loss of vis viva occurs, owing to the constituents of the binary
compound on their migration to the metals moving to the latter with a definite velocity and
then coming to rest, either with formation of a compound (ZnCl2) or by escaping in
the free state (H).

This loss is equivalent to the quantity of heat which is set free in the visibly occurring
chemical process, essentially, therefore, that produced on the solution of an equivalent of
zinc in the dilute acid."

Firstly, if the process goes on in pure form, no heat at all is set free in the
battery on solution of the zinc; the liberated energy is indeed converted directly into
electricity and only from this converted once again into heat by the resistance of the whole
circuit.

Secondly, vis viva is half the product of the mass and the square of the
velocity. Hence the above statement would read: the energy set free on solution of an
equivalent of zinc in dilute hydrochloric acid, ==so many calories, is likewise equivalent to
half the product of the mass of the ions and the square of the velocity with which they
migrate to the metals. Expressed in this way, the sentence is obviously false: the vis
viva appearing on the migration of the ions is far removed from being equivalent to the
energy set free by the chemical
process.[14] But if it were to be so,
no current would be possible, since there would be no energy remaining over for the current
in the remainder of the circuit. Hence the further remark is introduced that the ions come to
rest "either with formation of a compound (ZnCl2) or by escaping in
the free state." But if the loss of vis viva is to include also the energy changes
taking place on these two processes, then we have indeed arrived at a deadlock. For it is
precisely to these two processes taken together that we owe the whole liberated energy, so
that there can be absolutely no question here of a loss of vis viva, but at
most of a gain.

It is therefore obvious that Wiedemann himself did not mean anything definite by this
sentence, rather the "loss of vis viva" represents only the deus ex machina
which is to enable him to make the fatal leap from the old contact theory to the chemical
explanation of the current. In point of fact, the loss of vis viva has now performed
its function and is dismissed; henceforth the chemical process in the battery has undisputed
sway
as the sole source of energy for current formation, and the only remaining anxiety of our
author is as to how he can politely get rid from the current of the last relic of excitation
of electricity by the contact of chemically indifferent bodies, namely, the force of
separation active at the place of contact of the two metals.

Reading the above explanation of current formation given by Wiedemann, one could believe
oneself in the presence of a specimen of the kind of apologia that wholly - and half-credulous
theologians of almost forty years ago employed to meet the philologico-historical bible
criticism of Strauss, Wilke, Bruno Bauer, etc. The method is exactly the same, and it is
bound to be so. For in both cases it is a question of saving the heritage of
tradition from scientific thought. Exclusive empiricism, which at most allows thinking
in the form of mathematical calculation, imagines that it operates only with undeniable
facts. In reality, however, it operates predominantly with out-of-date notions, with the
largely obsolete products of thought of its predecessors, and such are positive and negative
electricity; the electric force of separation, the contact theory. These serve it as the
foundation of endless mathematical calculations in which, owing to the strictness of the
mathematical formulation, the hypothetical nature of the premises gets comfortably forgotten.
This kind of empiricism is as credulous towards the results of the thought of its
predecessors as it is sceptical in its attitude to the results of contemporary thought. For
it the experimentally established facts have gradually become inseparable from the
traditional interpretation associated with them; the simplest electric phenomenon is
presented falsely, e.g. by smuggling in the two electricities; this empiricism
cannot any longer describe the facts correctly, because the traditional
interpretation is woven into the description. In short, we have here in the field of the
theory of electricity a tradition just as highly developed as that in the field of theology.
And since in both fields the results of recent research, the establishment of hitherto
unknown or disputed facts and of the necessarily following theoretical conclusions, run
pitilessly counter to the old traditions, the defenders of these traditions find themselves
in the direst dilemma. They have to resort to all kinds of subterfuges and untenable
expedients, to the glossing over of irreconcilable contradictions, and thus finally land
themselves into a medley of contradictions from which they have no escape. It is this faith
in all the old theory of electricity that entangles Wiedemann here in the most hopeless
contradictions, simply owing to the hopeless attempt to reconcile rationally the old
explanation of the current by "contact force," with the modern one by liberation of chemical
energy.

It will perhaps be objected that the above criticism of Wiedemann's explanation of the
current rests on juggling with words. It may be objected that, although at the beginning
Wiedemann expresses himself somewhat carelessly and inaccurately, still he does finally give
the correct account in accord with the principle of the conservation of energy and so sets
everything right. As against this view, we give below another example, his description of the
process in the battery: zinc-dilute sulphuric acid-copper:

"If, however, the two plates are joined by a wire, a galvanic current arises ....
By the electrolytic process, one equivalent of hydrogen is given off at the copper
plate from the water of the dilute sulphuric acid, this hydrogen escaping in bubbles. At the
zinc there is formed one equivalent of oxygen which oxidises the zinc to form zinc oxide, the
latter becoming dissolved in the surrounding acid to form sulphuric zinc oxide." (I, pp.
592-3.)

To break up water into hydrogen and oxygen requires an amount of energy of 69,924 heat-
units for each molecule of water. From where then comes the energy in the above cell? "By the
electrolytic process." And from where does the electrolytic process get it? No answer is
given.

But Wiedemann further tells us, not once, but at least twice (I, p. 472 and p. 614), that
"according to recent knowledge the water itself is not decomposed," but that in our case it
is the sulphuric acid H2SO4 that splits
up into H2 on the one hand and into SO3+O
on the other hand, whereby under suitable conditions H2 and O can
escape in gaseous form. But this alters the whole nature of the process. The
H2 of the H2SO4
is directly replaced by the bivalent zinc, forming zinc sulphate,
ZnSO4. There remains over, on the one side
H2, on the other SO3+O. The two gases
escape in the proportions in which they unite to form water, the
SO3 unites with the water of the solvent to reform
H2SO4, i.e. sulphuric acid. The
formation of ZnSO4, however, develops sufficient energy not only to
replace and liberate the hydrogen of the sulphuric acid, but also to leave over a
considerable excess, which in our case is expended in forming the current. Hence the zinc
does not wait until the electrolytic process puts free oxygen at its disposal, in order first
to become oxidised and then to become dissolved in the acid. On the contrary, it enters
directly into the process, which only comes into being at all by this participation of
the zinc.

We see here how obsolete chemical notions come to the aid of the obsolete contact notions.
According to modern views, a salt is an acid in which hydrogen has been replaced by a metal.
The process under investigation confirms this view; the direct replacement of the hydrogen of
the acid by the zinc fully explains the energy change. The old view, adhered to by Wiedemann,
regards a salt as a compound of a metallic oxide with an acid and therefore speaks of
sulphuric zinc oxide instead of zinc sulphate. But to arrive at sulphuric zinc oxide in our
battery of zinc and sulphuric acid, the zinc must first be oxidised. In order to oxidise the
zinc fast enough, we must have free oxygen. In order to get free oxygen, we must assume
- since hydrogen appears at the copper plate - that the water is decomposed. In order to
decompose water, we need tremendous energy. How are we to get this? Simply "by the
electrolytic process" which itself cannot come into operation as long as its chemical end
product, the "sulphuric zinc oxide," has not begun to be formed. The child gives birth to the
mother.

Consequently, here again Wiedemann puts the whole course of the process absolutely the
wrong way round and upside down. And the reason is that he lumps together active and passive
electrolysis, two directly opposite processes, simply as electrolysis.

So far we have only examined the events in the battery, i.e. that process in
which an excess of energy is set free by chemical action and is converted into electricity by
the arrangements of the battery. But it is well known that this process can also be reversed:
the electricity of a constant current produced in the battery from chemical energy can, in
its turn, be reconverted into chemical energy in a decomposition cell inserted in the
circuit. The two processes are obviously the opposites of each other; if the first is
regarded as chemico-electric, then the second is electro-chemical. Both can take place in the
same circuit with the same substances. Thus, the voltaic pile from gas elements, the current
of which is produced by the union of hydrogen and oxygen to form water, can, in a
decomposition cell inserted in the circuit, furnish hydrogen and oxygen in the proportion in
which they form water. The usual mode
of view lumps these two opposite processes together under the single expression:
electrolysis, and does not even distinguish between active and passive electrolysis, between
an exciting liquid and a passive electrolyte. Thus Wiedemann treats of electrolysis in
general for 143 pages and then adds at the end some remarks on "electrolysis in the battery,"
in which, moreover, the processes in actual batteries only occupy the lesser part of the
seventeen pages of this section. Also in the "theory of electrolysis" that follows, this
contrast of battery and decomposition cell is not even mentioned, and anyone who looked for
some treatment of the energy changes in the circuit in the next chapter, "the influence of
electrolysis on the conduction resistance and the electromotive force in the circuit" would
be bitterly disappointed.

Let us now consider the irresistible "electrolytic process" which is able to separate
H2 from O without visible supply of energy, and which plays the
same role in the present section of the book as did previously the mysterious "electric force
of separation."

"Besides the primary, purely electrolytic process of separation of the ions, a
quantity of secondary, purely chemical processes, quite independent of the first,
take place by the action of the ions split off by the current. This action can take place on
the material of the electrodes and on the bodies that are decomposed, and in the case of
solutions also on the solvent." (I, p. 481.) Let us return to the above-mentioned battery:
zinc and copper in dilute sulphuric acid. Here, according to Wiedemann's own statement, the
separated ions are the H2 and O of the water. Consequently for him
the oxidation of the zinc and the formation of ZnSO4 is a
secondary, purely chemical process, independent of the electrolytic process, in spite of the
fact that it is only through it that the primary process becomes possible.

Let us now examine somewhat in detail the confusion that must necessarily arise from this
inversion of the true course of events:

Let us consider in the first place the so-called secondary processes in the decomposition
cell, of which Wiedemann puts forward some examples [15] (pp. 481, 482).

I. "The electrolysis of Na2SO4
dissolved in water. This "breaks up ... into 1 equivalent of
SO3+O ... and 1 equivalent of Na .... The latter, however,
reacts on the water solvent and splits off from it 1 equivalent of H, while 1 equivalent of
sodium is formed and becomes dissolved in the surrounding water."

The equation is

Na2SO4+2H2O==O+SO3+2NaOH+2H.

In fact, in this example the decomposition

Na2SO4==Na2+SO3+O

could be regarded as the primary electro-chemical process, and the further transformation

Na2+2H2O==2NaHO+2H

as the secondary, purely chemical one. But this secondary process is effected immediately at
the electrode where the hydrogen appears, the very considerable quantity of energy (111,810
heat-units for Na, O, H, aq. according to Julius Thomsen) thereby liberated is therefore, at
least for the most part, converted into electricity, and only a portion in the cell is
transformed directly into heat. But the latter can also happen to the chemical energy
directly or primarily liberated in the battery. The quantity of energy which has
thus
become available and converted into electricity, however, is to be subtracted from that which
the current has to supply for continued decomposition of the
Na2SO4 If the conversion of sodium into
hydrated oxide appeared in the first moment of the total process as a secondary
process, from the second moment on wards it becomes an essential factor of the total process
and so ceases to be secondary.

But yet a third process takes place in this decomposition cell:
SO3 combines with H2O to form
H2SO4, sulphuric acid, provided the
SO3 does not enter into combination with the metal of the positive
electrode, in which case again energy would be liberated. But this change does not
necessarily proceed immediately at the electrode, and consequently the quantity of energy
(21,320 heat-units, J. Thomsen) thereby liberated becomes converted wholly or mainly into
heat in the cell itself, and provides at most a very small portion of the electricity in the
current. The only really secondary process occurring in this cell is therefore not mentioned
at all by Wiedemann.

II. "If a solution of copper sulphate is electrolysed between a positive
copper electrode and a negative one of platinum, 1 equivalent of copper separates out for 1
equivalent of water decomposed at the negative platinum electrode, with simultaneous
decomposition of sulphuric acid in the same current circuit; at the positive electrode, 1
equivalent of SO4 should make its appearance; but this combines
with the copper of the electrode to form one equivalent of CuSO4,
which becomes dissolved in the water of the electrolysed solution."

In the modern chemical mode of expression we have, therefore, to represent the process as
follows: copper is deposited on the platinum; the liberated SO4,
which cannot exist by itself, splits up into SO3+O, the latter
escaping in the free state; the SO3 takes up
H2O from the aqueous solvent and forms
H2SO4, which again combines with the
copper of the electrode to form CuSO4, H2
being set free. Accurately speaking, we have here three processes: (1) the separation of Cu
and SO4; (2)
SO3+O+H2O==H2SO
4+O; (3)
H2SO4+Cu==H2+Cu
SO4. It is natural to regard the first as primary, the two others
as secondary. But if we inquire into the energy changes, we find that the first process is
completely compensated by a part of the third: the separation of copper from
SO4 by the reuniting of both at the other electrode. If we leave
out of account the energy required for shifting the copper from one electrode to the other,
and likewise the inevitable, not accurately determinable, loss of energy in the cell by
conversion into heat, we have here a case where the so-called primary process withdraws no
energy from the current. The current provides energy exclusively to make possible the
separation of H2 and O, which moreover is indirect, and this proves
to be the real chemical result of the whole process - hence, for carrying out a
secondary, or even tertiary, process.

Nevertheless, in both the above examples, as in other cases also, it is undeniable that
the distinction of primary and secondary processes has a relative justification. Thus in both
cases, among other things, water also is apparently decomposed and the elements of water
given off at the opposite electrodes. Since, according to the most recent experiments,
absolutely pure water comes as near as possible to being an ideal non-conductor, hence also a
non-electrolyte, it is important to show that in these and similar cases it is not the water
that is directly electro-chemically decomposed, but that the elements of water are separated
from the acid, in the formation of which here it is true the water solvent must participate.

III. "If one electrolyses hydrochloric acid simultaneously in two U-tubes
... using in one tube a zinc positive electrode and in the other tube one of copper, then
in the first tube a quantity of zinc 32.53 is dissolved, in the other a quantity of copper 2
x 32.7."

For the time being let us leave the copper out of account and consider the zinc. The
decomposition of HCl is regarded here as the primary process, the solution of Zn as
secondary.

According to this conception, therefore, the current brings to the decomposition cell from
outside the energy necessary for the separation of H and Cl, and after this separation is
completed the Cl combines with the Zn, whereby a quantity of energy is set free that is
subtracted from that required for separating H and Cl; the current needs only therefore to
supply the difference. So far everything agrees beautifully; but if we consider the two
amounts of energy more closely we find that the one liberated on the formation of
ZnCl2 is larger than that used up in separating 2HCl;
consequently, that the current not only does not need to supply energy, but on the contrary
receives energy. We are no longer confronted by a passive electrolyte, but by an
exciting fluid, not a decomposition cell but a battery, which strengthens the
current-forming voltaic pile by a new element; the process which we are supposed to conceive
as secondary becomes absolutely primary, becoming the source of energy of the whole process
and making the latter independent of the current supplied by the voltaic pile.

We see clearly here the source of the whole confusion prevailing in Wiedemann's
theoretical description. Wiedemann's point of departure is electrolysis; whether this is
active or passive, battery or decomposition cell, is all one to him: saw-bones is saw-bones,
as the sergeant-major
said to the doctor of philosophy doing his year's military service. And since it is easier to
study electrolysis in the decomposition cell than in the battery, he does, in fact, take the
decomposition cell as his point of departure, and he makes the processes taking place in it,
and the partly justifiable division of them into primary and secondary, the measure of the
altogether reverse processes in the battery, not even noticing when his decomposition cell
becomes surreptitiously transformed into a battery. Hence he is able to put forward the
statement: "the chemical affinity that the separated substances have for the electrodes has
no influence on the electrolytic process as such" (I, p. 471), a sentence which in this
absolute form, as we have seen, is totally false. Hence, further, his threefold theory of
current formation: firstly, the old traditional one, by means of pure contact; secondly, that
derived by means of the abstractly conceived electric force of separation, which in an
inexplicable manner obtains for itself or for the "electrolytic process" the requisite energy
for splitting apart the H and Cl in the battery and for forming a current as well; and
finally, the modern, chemico-electric theory which demonstrates the source of this energy in
the algebraic sum of the chemical reactions in the battery. Just as he does not notice that
the second explanation overthrows the first, so also he has no idea that the third in its
turn overthrows the second. On the contrary, the principle of the conservation of energy is
merely added in a quite superficial way to the old theory handed down from routine, just as a
new geometrical theorem is appended to an earlier one. He has no inkling that this principle
makes necessary a revision of the whole traditional point of view in this as in all other
fields of natural science. Hence Wiedemann confines himself to noting the principle in his
explanation of the current, and then calmly puts
it on one side, taking it up again only right at the end of the book, in the chapter on the
work performed by the current. Even in the theory of the excitation of electricity by contact
(I, p. 781 et seq.) the conservation of energy plays no role at all in relation to
the chief subject dealt with, and is only incidentally brought in for throwing light on
subsidiary matters: it is and remains a " secondary process."

Let us return to the above example III. There the same current was used
to electrolyse hydrochloric acid in two U-tubes, but in one there was a positive electrode of
zinc, in the other, the positive electrode used was of copper. According to Faraday's basic
law of electrolysis, the same galvanic current decomposes in each cell equivalent quantities
of electrolyte, and the quantities of the substances liberated at the two electrodes are also
in proportion to their equivalents (I, p. 470). In the above case it was found that in the
first tube a quantity of zinc 32.53 was dissolved, and in the other a quantity of copper 2 x
31.7. "Nevertheless," continues Wiedemann, "this is no proof for the equivalence of these
values. They are observed only in the case of very weak currents with the formation of zinc
chloride ... on the one hand, and of copper chloride ... on the other. In the case of
denser currents, with the same amount of zinc dissolved, the quantity of dissolved copper
would sink with formation of increasing quantities of chloride ... up to 31.7."

It is well known that zinc forms only a single compound with chlorine, zinc chloride,
ZnCl; copper on the other hand forms two compounds, cupric chloride,
CuCl2, and cuprous chloride,
Cu2Cl2. Hence the process is that the
weak current splits off two copper atoms from the electrode for each two chlorine atoms, the
two copper atoms remaining united by one of their two
valencies, while their two free valencies unite with the two chlorine atoms:

Cu

-

-

Cl

Cu

-

-

Cl

On the other hand, if the current becomes stronger, it splits the copper atoms apart
altogether, and each one unites with two chlorine atoms.

Cl

/

Cu

\

Cl

In the case of currents of medium strength, both compounds are formed side by side. Thus it
is solely the strength of the current that determines the formation of one or the other
compound, and therefore the process is essentially electro-chemical, if this word
has any meaning at all. Nevertheless Wiedemann declares explicitly that it is secondary,
hence not electro-chemical, but purely chemical.

The above experiment is one performed by Renault (1867) and is one of a whole series of
similar experiments in which the same current is led in one U-tube through salt solution
(positive electrode - zinc), and in another cell through a varying electrolyte with various
metals as the positive electrode. The amounts of the other metals dissolved here for each
equivalent of zinc diverged very considerably, and Wiedemann gives the results of the whole
series of experiments which, however, in point of fact, are mostly self-evident chemically
and could not be otherwise. Thus, for one equivalent of zinc, only two-thirds of an
equivalent of gold is dissolved in hydrochloric acid. This can only appear remarkable if,
like Wiedemann, one adheres to the old equivalent weights and writes ZnCl for zinc chloride,
according to which both the chlorine and the zinc appear in the chloride with only a
single valency. In reality two
chlorine atoms are included to one zinc atom, ZnCl2, and as soon as
we know this formula we see at once that in the above determination of equivalents, the
chlorine atom is to be taken as the unit and not the zinc atom. The formula for gold
chloride, however, is AuCl3, from which it is at once seen that
3ZnCl2 contains exactly as much chlorine as
2AuCl3, and so all primary, secondary, and tertiary processes in
the battery or cell are compelled to transform, for each part by weight[16] of zinc converted into zinc chloride, neither more
nor less than two-thirds of a part by weight of gold into gold chloride. This holds
absolutely unless the compound AuCl3[17] also could be prepared by galvanic means, in which
case two equivalents of gold even would have to be dissolved for one equivalent of zinc, when
also similar variations according to the current strength could occur as in the case of
copper and chlorine mentioned above. The value of Renault's researches consists in the fact
that they show how Faraday's law is confirmed by facts that appear to contradict it. But what
they are supposed to contribute in throwing light on secondary processes in electrolysis is
not evident.

Wiedemann's third example led us again from the decomposition cell to the battery, and in
fact the battery offers by far the greatest interest when one investigates the electrolytic
processes in relation to the transformations of energy taking place. Thus we not infrequently
encounter batteries in which the chemico-electric processes seem to take place in direct
contradiction to the law of the conservation of energy and in opposition to chemical
affinity.

According to Poggendorff's measurements, the battery: zinc - concentrated salt solution -
platinum,
provides a current of strength 134.6. Hence we have here quite a respectable
quantity of electricity, one third more than in the Daniell cell. What is the source of the
energy appearing here as electricity? The "primary" process is the replacement of sodium in
the chlorine compound by zinc. But in ordinary chemistry it is not zinc that replaces sodium,
but vice versa, sodium replacing zinc from chlorine and other compounds. The
"primary" process, far from being able to give the current the above quantity of energy, on
the contrary requires itself a supply of energy from outside in order to come into being.
Hence, with the mere "primary" process we are again at a standstill. Let us look, therefore,
at the real process. We find that the change is not

Zn+2NaCl==ZnCl2+2Na,

but

Zn+2NaCl+2H2O==ZnCl2+2NaOH+H2.

In other words, the sodium is not split off in the free state at the negative electrode,
but forms a hydroxide as in the above example I (pp. 118-119). To calculate
the energy changes taking place here, Julius Thomsen's determinations provide us at least
with certain important data. According to them, the energy liberated on combination is as
follows:

(ZnCl2)==97,210,
(ZnCl2, aqua)==15,630,

making a total for dissolved

zinc chloride

==

112,840

heat-

units.

2 (Na, O, H, aqua)

==

223,620

"

"

336,460

"

"

Deducting consumption of energy on the separations:

2(Na, Cl, aq.)

==

193,020

heat-

units.

2(H2O)

==

136,720

"

"

329,740

"

"

The excess of liberated energy equals 6,720 heat-units.

This amount is obviously small for the current strength obtained, but it suffices to
explain, on the one hand, the separation of the sodium from chlorine, and on the other hand,
the current formation in general.

We have here a striking example of the fact that the distinction of primary and secondary
processes is purely relative and leads us ad absurdum as soon as we take it
absolutely. The primary electrolytic process, taken alone, not only cannot produce any
current, but cannot even take place itself. It is only the secondary, ostensibly purely
chemical process that makes the primary one possible and, moreover, supplies the whole
surplus energy for current formation. In reality, therefore, it proves to be the primary
process and the other the secondary one. When the rigid differences and opposites, as
imagined by the metaphysicians and metaphysical natural scientists, were dialectically
reversed into their opposites by Hegel, it was said that he had twisted the words in their
mouths. But if nature itself proceeds exactly like old Hegel, it is surely time to examine
the matter more closely.

With greater justification one can regard as secondary those processes which, while taking
place in consequence of the chemico-electric process of the battery or the electro-
chemical process of the decomposition cell, do so independently and separately, occurring
therefore at the same distance from the electrodes. The energy changes taking place in such
secondary processes likewise do not enter into the electric process; directly they neither
withdraw energy from it nor supply energy to it. Such processes occur very frequently in the
decomposition cell; we saw an instance in the example I above on the
formation of sulphuric acid during electrolysis of sodium sulphate. They are, however, of
lesser interest here. Their occurrence in the battery, on the other hand, is of greater
practical importance. For although they do
not directly supply energy to, or withdraw it from, the chemico-electric process,
nevertheless they alter the total available energy present in the battery and thus affect it
indirectly.

There belong here, besides subsequent chemical changes of the ordinary kind, the phenomena
that occur when the ions are liberated at the electrodes in a different condition from that
in which they usually occur in the free state, and when they pass over to the latter only
after moving away from the electrodes. In such cases the ions can assume a different density
or a different state of aggregation. They can also undergo considerable changes in regard to
their molecular constitution, and this case is the most interesting. In all these cases, an
analogous heat change corresponds to the secondary chemical or physical change of the ions
taking place at a certain distance from the electrodes; usually heat is set free, in some
cases it is consumed. This heat change is, of course, restricted in the first place to the
place where it occurs: the liquid in the battery or decomposition cell becomes warmer or
cooler while the rest of the circuit remains unaffected. Hence this heat is called
local heat. The liberated chemical energy available for conversion into electricity
is, therefore, diminished or increased by the equivalent of this positive or negative local
heat produced in the battery. According to Favre, in a battery with hydrogen peroxide and
hydrochloric acid two-thirds of the total energy set free is consumed as local heat; the
Grove cell, on the other hand, on closing the circuit became considerably cooler and
therefore supplied energy from outside to the circuit by absorption of heat. Hence we see
that these secondary processes also react on the primary one. We can make whatever approach
we like; the distinction between primary and secondary processes remains merely a relative
one and is regularly suspended in the interaction
of the one with the other. If this is forgotten and such relative opposites treated as
absolute, one finally gets hopelessly involved in contradictions, as we have seen above.

As is well known, on the electrolytic separation of gases the metal electrodes become
covered with a thin layer of gas; in consequence the current strength decreases until the
electrodes are saturated with gas, whereupon the weakened current again becomes constant.
Favre and Silbermann have shown that local heat arises also in such a decomposition cell;
this local heat, therefore, can only be due to the fact that the gases are not liberated at
the electrodes in the state in which they usually occur, but that they are only brought into
their usual state, after their separation from the electrode, by a further process bound up
with the development of heat. But what is the state in which the gases are given off at the
electrodes? It is impossible to express oneself more cautiously on this than Wiedemann does.
He terms it "a certain," an "allotropic," an "active," and finally, in the case of oxygen,
several times an "ozonised" state. In the case of hydrogen his statements are still more
mysterious. Incidentally, the view comes out that ozone and, hydrogen peroxide are the forms
in which this "active" state is realised. Our author is so keen in his pursuit of ozone that
he even explains the extreme electro-negative properties of certain peroxides from the fact
that they possibly "contain a part of the oxygen in the ozonised state!" (I, p. 57.)
Certainly both ozone and hydrogen peroxide are formed on the so-called decomposition of
water, but only in small quantities. There is no basis at all for assuming that in the case
mentioned local heat is produced first of all by the origin and then by the decomposition of
any large quantities of the above two compounds. We do not know the heat of formation
of ozone, O3, from free oxygen atoms. According to
Berthelot the heat of formation of hydrogen peroxide from H2O
(liquid)+O=-21,480; the origin of this compound in any large amount would therefore give rise
to a large excess of energy (about 30 per cent. of the energy required for the separation of
H2 and O), which could not but be evident and demonstrable.
Finally, ozone and hydrogen peroxide would only take oxygen into account (apart from current
reversals, where both gases would come together at the same electrode), but not hydrogen. Yet
the latter also escapes in an "active" state, so much so that in the combination: potassium
nitrate solution between platinum electrodes, it combines directly with the nitrogen split
off from the acid to form ammonia.

In point of fact, all these difficulties and doubts have no existence. The electrolytic
process has no monopoly of splitting off bodies "in an active state." Every chemical
decomposition does the same thing. It splits off the liberated chemical elements in the first
place in the form of free atoms of O, H, N, etc., which only after their liberation can unite
to form molecules, O2, H2,
N2, etc., and on thus uniting give off a definite, though up-to-now
still undetermined,[18] quantity of
energy which appears as heat. But during the infinitesimal moment of time when the atoms are
free, they are the bearers of the total quantity of energy that they can take up at all;
while possessed of their maximum energy they are free to enter into any combination offered
them. Hence they are "in an active state" in contrast to the molecules
O2, H2, N2,
which have already surrendered a part of this energy and cannot enter into combination with
other elements without this quantity of energy surrendered
being re-supplied from outside. We have no need, therefore, to resort to ozone and hydrogen
peroxide, which themselves are only products of this active state. For instance, we can
undertake the above-mentioned formation of ammonia on electrolysis of potassium nitrate even
without a battery, simply by chemical means, by adding to nitric acid or a nitrate solution a
liquid in which hydrogen is set free by a chemical process. In both cases the active state of
the hydrogen is the same. But the interesting point about the electrolytic process is that
here the transitory existence of the free atoms becomes as it were tangible. The process here
is divided into two phases: the electrolysis provides free atoms at the electrodes, but their
combination to form molecules occurs at some distance from the electrodes. However
infinitesimally minute this distance may be compared to measurements where masses are
concerned, it suffices to prevent the energy liberated on formation of the molecules being
used for the electric process, at least for the most part, and so determines its conversion
into heat - the local heat in the battery. But it is owing to this that the fact is
established that the elements are split off as free atoms and for a moment have existed in
the battery as free atoms. This fact, which in pure chemistry can only be established by
theoretical conclusions,[19] is here
proved experimentally, in so far as this is possible without sensuous perception of the atoms
and molecules themselves. Herein lies the high scientific importance of the so-called local
heat of the battery.

The conversion of chemical energy into electricity by means of the battery is a process
about whose course we know next to nothing, and which we shall get to know in more detail
only when the modus operandi of electric motion itself becomes better known.

The battery has ascribed to it an "electric force of separation" which is given for each
particular battery. As we saw at the outset, Wiedemann conceded that this electric force of
separation is not a definite form of energy. On the contrary, it is primarily nothing more
than the capacity, the property, of a battery to convert a definite quantity of liberated
chemical energy into electricity in unit time. Throughout the whole course of events, this
chemical energy itself never assumes the form of an "electric force of separation," but, on
the contrary, at once and immediately takes on the form of so-called "electromotive force"
i.e. of electric motion. If in ordinary life we speak of the force of a steam engine
in the sense that it is capable in unit time of converting a definite quantity of heat into
the motion of masses, this is not a reason for introducing the same confusion of ideas into
scientific thought also. We might just as well speak of the varying force of a pistol, a
carbine, a smooth-bored gun, and a blunderbuss, because, with equal gunpowder charges and
projectiles of equal weight, they shoot varying distances. But here the wrongness of the
expression is quite obvious. Everyone knows that it is the ignition of the gunpowder charge
that drives the bullet, and that the varying range of the weapon is only determined by the
greater or lesser dissipation of energy according to the length of the barrel, the form of
the projectile, and the tightness of its fitting. But it is the same for steam power and for
the electric force of separation. Two steam engines - other conditions being equal,
i.e. assuming the quantity of energy liberated in equal periods of time to be equal
in both - or two galvanic batteries, of which the same thing holds good, differ as regards
performance of work only owing to their greater or lesser dissipation of energy. And if until
now all armies have been able to develop the technique of firearms without the assumption of
a
special shooting force of weapons, the science of electricity has absolutely no excuse for
assuming an "electric force of separation" analogous to this shooting force, a force which
embodies absolutely no energy and which therefore of itself cannot perform a millionth of a
milligram-metre of work.

The same thing holds good for the second form of this "force of separation," the "electric
force of contact of metals" mentioned by Helmholtz. It is nothing but the property of metals
to convert on their contact the existing energy of another form into electricity. Hence it is
likewise a force that does not contain a particle of energy. If we assume with Wiedemann that
the source of energy of contact electricity lies in the vis viva of the motion of
adhesion, then this energy exists in the first place in the form of this mass motion and on
its vanishing becomes converted immediately into electric motion, without even for a moment
assuming the form of an "electric force of contact."

And now we are assured in addition that the electromotive force, i.e. the
chemical energy, reappearing as electric motion is proportional to this "electric force of
separation," which not only contains no energy, but owing to the very conception of it
cannot contain any! This proportionality between non-energy and energy obviously
belongs to the same mathematics as that in which there figures the "ratio of the unit of
electricity to the milligram." But the absurd form, which owes its existence only to the
conception of a simple property as a mystical force, conceals a quite
simple tautology: the capacity of a given battery to convert liberated chemical energy into
electricity is measured - by what? By the quantity of the energy reappearing in the circuit as
electricity in relation to the chemical energy consumed in the battery. That is all.

In order to arrive at an electric force of separation,
one must take seriously the device of the two electric fluids. To convert this from its
neutrality to its polarity, hence to split it apart, requires a certain expenditure of energy
- the electric force of separation. Once separated, the two electricities can, on being
reunited, again give off the same quantity of energy - electromotive force. But since nowadays
no one, not even Wiedemann, regards the two electricities as having a real existence, it
means that one is writing for a defunct public if one deals at length with such a point of
view.

The basic error of the contact theory consists in the fact that it cannot divorce itself
from the idea that contact force or electric force of separation is a source of
energy, which of course was difficult when the mere capacity of an apparatus to bring
about transformation of energy had been converted into a force; for indeed, a
force ought precisely to be a definite form of energy. Because Wiedemann cannot rid
himself of this unclear notion of force, although alongside of it the modern ideas of
indestructible and uncreatable energy have been forced upon him, he falls into his
nonsensical explanation of the current, No. 1, and into all the later demonstrated
contradictions.

If the expression "electric force of separation" is directly contrary to reason, the other
"electromotive force" is at least superfluous. We had heat engines long before we had
electro-motors, and yet the theory of heat has been developed quite well without any special
thermo-motor force. Just as the simple expression heat includes all phenomena of motion that
belong to this form of energy, so also can the expression electricity in its own sphere.
Moreover, very many forms of action of electricity are not at all directly "motor": the
magnetisation of iron, chemical decomposition, conversion into heat. And finally, in every
natural science,
even in mechanics, it is always an advance if the word force can somehow be got rid
of.[20]

We saw that Wiedemann did not accept the chemical explanation of the processes in the
battery without a certain reluctance. This reluctance continually attacks him; where he can
blame anything on the so-called chemical theory, this is certain to occur. Thus, "it is by no
means established that the electromotive force is proportional to the intensity of chemical
action." (I, p. 791.) Certainly not in every case; but where this proportionality does not
occur, it is only a proof that the battery has been badly constructed, that dissipation of
energy takes place in it. For that reason Wiedemann is quite right in paying no attention in
his theoretical deductions to such subsidiary circumstances which falsify the purity of the
process, but in simply assuring us that the electromotive force of a cell is equal to the
mechanical equivalent of the chemical action taking place in it in unit time with unit
intensity of current.

In another passage we read:

"That further, in the acid-alkali battery, the combination of acid and alkali is not the
cause of current formation follows from the experiments paragraph 61 (Becquerel and Fechner),
paragraph 260 (Dubois-Raymond), and paragraph 261 (Worm-Müller), according to which in
certain cases when these are present in equivalent quantities no current makes its
appearance, and likewise from the experiments (Henrici) mentioned in paragraph 62, that on
interposing a solution of potassium nitrate between the potassium hydroxide and nitric acid,
the electromotive force makes its appearance in the same way as without this interposition."
(I, p. 791.)

The question whether the combination of acid and alkali is the cause of current formation
is a matter of very serious concern for our author. Put in this form it is very easy to
answer. The combination of acid and alkali is first of all the cause of a salt being
formed with liberation of energy. Whether this energy wholly or partly takes the form of
electricity depends on the circumstances under which it is liberated. For instance, in the
battery: nitric acid and potassium hydroxide between platinum electrodes, this will be at
least partially the case, and it is a matter of indifference for the formation of
the current whether a potassium nitrate solution is interposed between the acid and alkali or
not, since this can at most delay the salt formation but not prevent it. If, however, a
battery is formed like one of Worm-Müller's, to which Wiedemann constantly refers, where the
acid and alkali solution is in the middle, but a solution of their salt at both ends, and in
the same concentration as the solution that is formed in the battery, then it is obvious that
no current can arise, because on account of the end members - since everywhere identical
bodies are formed - no ions can be produced. Hence the conversion of the liberated
energy into electricity has been prevented in as direct a manner as if the circuit had not
been closed; it is therefore not to be wondered at that no current is obtained. But that acid
and alkali can in general produce a current is proved by the battery: carbon, sulphuric acid
(one part in ten of water), potassium hydroxide (one part in ten of water), carbon, which
according to Raoult has a current strength of 73.[21] And that, with suitable arrangement of the battery,
acid and alkali can provide a current strength corresponding to the large quantity of energy
set free on their combination, is seen from the
fact that the most powerful batteries known depend almost exclusively on the formation of
alkali salts, e.g. that of Wheatstone: platinum, platinic chloride, potassium
amalgam - current strength 230; lead peroxide, dilute sulphuric acid, potassium amalgam==326;
manganese peroxide instead of lead peroxide==280; in each case, if zinc amalgam was employed
instead of potassium amalgam, the current strength fell almost exactly by 100. Similarly in
the battery: manganese dioxide, potassium permanganate solution, potassium hydroxide,
potassium, Beetz obtained the current strength 302, and further: platinum, dilute sulphuric
acid, potassium==293.8 ; Joule: platinum, nitric acid, potassium hydroxide, potassium
amalgam==302. The "cause" of these exceptionally strong current strengths is certainly the
combination of acid and alkali, or alkali metal, and the large quantity of energy thereby
liberated.

A few pages further on it is again stated:

"It must, however, be carefully borne in mind that the equivalent in work of the whole
chemical action taking place at the place of contact of the heterogeneous bodies is not to be
directly regarded as the measure of the electromotive force in the circuit. When, for
instance, in the acid-alkali battery (iterum Crispinus!) of Becquerel, these two
substances combine, when carbon is consumed in the battery: platinum, molten potassium
nitrate, carbon, when the zinc is rapidly dissolved in an ordinary cell of copper, impure
zinc, dilute sulphuric acid, with formation of local currents, then a large part of the work
produced (it should read: energy liberated) in these chemical processes . . . is converted
into heat and is thus lost for the total current circuit." (I, p. 798.)

All these processes are to be referred to loss of energy in the battery; they do not
affect the fact that the electric motion arises from transformed chemical energy, but only
affect the quantity of energy transformed.

Electricians have devoted an endless amount of time and trouble to composing the most
diverse batteries and measuring their "electromotive force." The experimental material thus
accumulated contains very much of value, but certainly still more that is valueless. For
instance, what is the scientific value of experiments in which "water" is employed as the
electrolyte, when, as has now been proved by F. Kohlrausch, water is the worst conductor and
therefore also the worst electrolyte,[22] and where, therefore, it is not the water but its
unknown impurities that caused the process? And yet, for instance, almost half of all
Fechner's experiments depend on such employment of water, even his "experimentum
crucis," by which he sought to establish the contact theory impregnably on the ruins of
the chemical theory. As is already evident from this, in almost all such experiments, a few
only excepted, the chemical processes in the battery, which however form the source of the
so-called electromotive force, remain practically disregarded. There are, however, a number
of batteries whose chemical composition does not allow of any certain conclusion being drawn
as to the chemical changes proceeding in them when the current circuit is closed. On the
contrary, as Wiedemann (I, p. 797) says, it is "not to be denied that we are by no means in
all cases able to obtain an insight into the chemical attractions in the battery." Hence,
from the ever more important chemical aspect, all such experiments are valueless in so far as
they are not repeated with these processes under control.

In these experiments it is indeed only quite by way of
exception that any account is taken of the energy changes taking place in the battery. Many
of them were made before the law of the equivalence of motion was recognised in natural
science, but as a matter of custom they continue to be dragged from one textbook into another
without being controlled or their value summed up. It has been said that electricity has no
inertia (which has about as much sense as saying velocity has no specific gravity), but this
certainly cannot be said of the theory of electricity.

So far, we have regarded the galvanic cell as all arrangement in which, in consequence of
the contact relations established, chemical energy is liberated in some way for the time
being unknown, and converted into electricity. We have likewise described the decomposition
cell as an apparatus in which the reverse process is set up, electric motion being converted
into chemical energy and used up as such. In so doing we had to put in the foreground the
chemical side of the process that has been so much neglected by electricians, because this
was the only way of getting rid of the lumber of notions handed down from the old contact
theory and the theory of the two electric fluids. This once accomplished, the question was
whether the chemical process in the battery takes place under the same conditions as outside
it, or whether special phenomena make their appearance that are dependent on the electric
excitation.

In every science, incorrect notions are, in the last resort, apart from errors of
observation, incorrect notions of correct facts. The latter remain even when the former are
shown to be false. Although we have discarded the old contact theory, the established facts
remain, of which they were supposed to be the explanation. Let us consider these and with
them the electric aspect proper of the process in the battery.

It is not disputed that on the contact of heterogeneous
bodies, with or without chemical changes, an excitation of electricity occurs which can be
demonstrated by means of an electroscope or a galvanometer. As we have already seen at the
outset, it is difficult to establish in a particular battery the source of energy of these in
themselves extremely minute phenomena of motion; it suffices that the existence of such an
external source is generally conceded.

In 1850-53, Kohlrausch published a series of experiments in which he assembled the separate
components of a battery in pairs and tested the static electric stresses produced in each
case; the electromotive force of the cell should then be composed of the algebraic sum of
these stresses. Thus, taking the stress of Zn/Cu==100, he calculates the relative strengths of
the Daniell and Grove cells as follows:

For the Daniell cell:

Zn/Cu+amalg.Zn/H2SO4+Cu/SO4==100+149-21==228.

For the Grove cell:

Zn/Pt+amalg.Zn/H2SO4+Pt/HNO3==107+149+149==405,

which closely agrees with the direct measurement of the current strengths of these cells.
These results, however, are by no means certain. In the first place, Wiedemann himself calls
attention to the fact that Kohlrausch only gives the final result but "unfortunately no
figures for the results of the separate experiments." In the second place, Woodman himself
repeatedly recognises that all attempts to determine quantitatively the electric excitation
on contact of metals, and still more on contact of metal and fluid, are at least very
uncertain on account of the numerous unavoidable sources of error. If, nevertheless, lie
repeatedly uses Kohlrausch's figures in his calculations, we shall do better not to follow
him here, the more so
as another means of determination is available which is not open to these objections.

If the two exciting plates of a battery are immersed in the liquid and then joined into a
circuit by the terminals of a galvanometer, according to Wiedemann, "the initial deflection
of its magnetic needle, before chemical changes have altered the strength of the electric
excitation, is a measure of the sum of electromotive forces in the circuit." Batteries of
various strengths, therefore, give initial deflections of various strengths, and the
magnitude of these initial deflections is proportional to the current strength of the
corresponding batteries.

It looks as if we had here tangibly before our eyes the "electric force of separation,"
the "contact force," which causes motion independently of any chemical action. And this in
fact is the opinion of the whole contact theory. In reality we are confronted here by a
relation between electric excitation and chemical action that we have not yet investigated.
In order to pass to this subject, we shall first of all examine rather more closely the so-
called electromotive law; in so doing, we shall find that here also the traditional contact
notions not only provide no explanation, but once again directly bar the way to an
explanation.

If in any cell consisting of two metals and a liquid, e.g. zinc, dilute
hydrochloric acid, and copper, one inserts a third metal such as a platinum plate, without
connecting it to the external circuit by a wire, then the initial deflection of the
galvanometer will be exactly the same as without the platinum plate. Consequently it
has no effect on the excitation of electricity. But it is not permissible to express this so
simply in electromotive language. Hence one reads:

"The sum of the electromotive forces of zinc and platinum and platinum and copper now
takes the
place of the electromotive force of zinc and copper in the liquid. Since the path of the
electricities is not perceptibly altered by the insertion of the platinum plate, we can
conclude from the identity of the galvanometer readings in the two cases, that the
electromotive force of zinc and copper in the liquid is equal to that of zinc and platinum
plus that of platinum and copper in the same liquid. This would correspond to Volta's theory
of the excitation of electricity between the metals as such. The result, which holds good for
all liquids and metals, is expressed by saying: On their electromotive excitation by liquids,
metals follow the law of the voltaic series. This law is also given the name of the
electromotive law." (Wiedemann, I, p. 62.)

In saying that in this combination the platinum does not act at all as an exciter of
electricity, one expresses what is simply a fact. If one says that it does act as an exciter
of electricity, but in two opposite directions with equal strength so that the effect is
neutralised, the fact is converted into a hypothesis merely for the sake of doing honour to
the "electromotive force." In both cases the platinum plays the role of a fictitious person.

During the first deflection there is still no closed circuit. The acids, being
undecomposed,[23] do not conduct;
they can only conduct by means of the ions. If the third metal has no influence on the first
deflection, this is simply the result of the fact that it is still isolated.

How does the third metal behave after the establishment of the constant current
and during the latter?

In the voltaic series of metals in most liquids, zinc lies after the alkali metals fairly
close to the positive end and platinum at the negative end, copper being
between the two. Hence, if platinum is put as above between copper and zinc it is negative to
them both. If the platinum had any effect at all, the current in the liquid would have to
flow to the platinum both from the zinc and from the copper, that is away from both
electrodes to the unconnected platinum; which would be a contradictio in adjectio.
The basic condition for the action of several different metals in the battery consists
precisely in their being connected among themselves externally to the circuit. An
unconnected, superfluous metal in the battery acts as a non-conductor; it can neither form
ions nor allow them to pass through, and without ions we know of no conduction in
electrolytes. Hence it is not merely a fictitious person, it even stands in the way by
forcing the ions to go round it.

The same thing holds good if we connect the zinc and platinum, leaving the copper
unconnected in the middle; here the latter, if it had any effect at all, would produce a
current from the zinc to the copper and another from the copper to the platinum; hence it
would have to act as a sort of intermediary electrode and give off hydrogen on the side
turned towards the zinc, which again is impossible.

If we discard the traditional electromotive mode of expression the case becomes extremely
simple. As we have seen, the galvanic battery is an apparatus in which chemical energy is
liberated and transformed into electricity. It consists as a rule of one or more liquids and
two metals as electrodes, which must be connected together by a conductor outside the
liquids. This completes the apparatus. Anything else that is dipped unconnected into the
exciting liquid, whether metal, glass, resin, or whatever you like, cannot participate in the
chemico-electric process taking place in the battery, in the formation of the current, so
long as the liquid is not chemically altered; it can at most hinder the
process. Whatever the capacity for exciting electricity of a third metal dipped into the
liquid may be, or that of one or both electrodes of the battery, it cannot have any effect so
long as this metal is not connected to the circuit outside the liquid.

Consequently, not only is Wiedemann's derivation, as given above, of the so-
called electromotive law false, but the interpretation which he gives to this law is also
false. One can speak neither of a compensating electromotive activity of the unconnected
metal, since the sole condition for such activity is cut off from the outset; nor can the so-
called electromotive law be deduced from a fact which lies outside the sphere of this law.

In 1845, old Poggendorff published a series of experiments in which he measured the
electromotive force of various batteries, that is to say the quantity of electricity supplied
by each of them in unit time.[24] Of
these experiments, the first twenty-seven are of special value, in each of which three given
metals were one after another connected in the same exciting liquid to three different
batteries, and the latter investigated and compared as regards the quantity of electricity
produced. As a good adherent of the contact theory, Poggendorff also put the third metal
unconnected in the battery in each experiment and so had the satisfaction of convincing
himself that in all eighty-one batteries this third metal remained a pure inactive element in
the combination. But the significance of these experiments by no means consists in this fact
but rather in the confirmation and establishment of the correct meaning of the so-called
electromotive law.

Let us consider the above series of batteries in which zinc, copper, and platinum are
connected together in pairs in dilute hydrochloric acid. Here Poggendorff
found the quantities of electricity produced to be as follows, taking that of a Daniell cell
as 100:

Zinc-copper

..

..

78.8

Copper-platinum

..

74.3

Total

..

..

153.1

Zinc-platinum

..

..

153.7

Thus, zinc in direct connection with platinum produced almost exactly the same quantity of
electricity as zinc-copper copper-platinum. The same thing occurred in all other batteries,
whatever liquids and metals were employed. When, from a series of metals in the same exciting
liquid, batteries were formed in such a way that in each case, according to the voltaic
series valid for this liquid, the second, third, fourth, etc., one after the other were made
to serve as negative electrodes for the preceding one and as positive electrodes for that
which followed, then the sum of the quantities of electricity produced by all these batteries
is equal to the quantity of electricity produced by a battery formed directly between the two
end members of the whole metallic series. For instance, in dilute hydrochloric acid the sum
total of the quantities of electricity produced by the batteries zinc-zinc, zinc-iron, iron-
copper, copper-silver, and silver-platinum, would be equal to that produced by the battery:
zinc-platinum. A pile formed from all the cells of the above series would, other things being
equal, be exactly neutralised by the introduction of a zinc-platinum cell with a current of
the opposite direction.

In this form, the so-called electromotive law has a real and considerable significance. It
reveals a new aspect of the inter-connection between chemical and electrical action.
Hitherto, on investigating mainly the source of energy of the galvanic current, this
source,
the chemical change, appeared as the active side of the process; the electricity was produced
from it and therefore appeared primarily as passive. Now this is reversed. The electric
excitation determined by the constitution of the heterogeneous bodies put into contact in the
battery can neither add nor subtract energy from the chemical action (other than by
conversion of liberated energy into electricity). It can, however, according as the battery
is made up, accelerate or slow down this action.

If the battery, zinc-dilute hydrochloric acid-copper, produced in unit time only half as
much electricity for the current as the battery, zinc-dilute hydrochloric acid-platinum, this
means in chemical terms that the first battery produces in unit time only half as much zinc
chloride and hydrogen as the second. Hence the chemical action has been doubled, although
the purely chemical conditions for this action have remained the same. The electric
excitation has become the regulator of the chemical action; it appears now as the active
side, the chemical action being the passive side.

Thus, it becomes comprehensible that a number of processes previously regarded as purely
chemical now appear as electro-chemical. Chemically pure zinc is not attacked at all by
dilute acid, or only very weakly; ordinary commercial zinc, on the other hand, is rapidly
dissolved with formation of a salt and production of hydrogen; it contains an admixture of
other metals and carbon, which make their appearance in unequal amounts at various places of
the surface. Local currents are formed in the acid between them and the zinc itself, the zinc
areas forming the positive electrodes and the other metals the negative electrodes, the
hydrogen bubbles being given off on the latter. Likewise the phenomenon that when iron is
dipped into a solution of copper sulphate it becomes covered with a
layer of copper is now seen to be an electro-chemical phenomenon, one determined by the
currents which arise between the heterogeneous areas of the surface of the iron.

In accordance with this we find also that the voltaic series of metals in liquids
corresponds on the whole to the series in which metals replace one another from their
compounds with halogens and acid radicles. At the extreme negative end of the voltaic series
we regularly find the metals of the gold group, gold, platinum, palladium, rhodium, which
oxidise with difficulty, are little or not at all attacked by acids, and which are easily
precipitated from their salts by other metals. At the extreme positive end are the alkali
metals which exhibit exactly the opposite behaviour: they are scarcely to be split off from
their oxides except with the greatest expenditure of energy; they occur in nature almost
exclusively in the form of salts, and of all the metals they have by far the greatest
affinity for halogens and acid radicles. Between these two come the other metals in somewhat
varying sequence, but such that on the whole electrical and chemical behaviour correspond to
one another. The sequence of the separate members varies according to the liquids and has
hardly been finally established for any single liquid. It is even permissible to doubt
whether there exists such an absolute voltaic series of metals for any single
liquid. Given suitable batteries and decomposition cells, two pieces of the same metal can
act as positive and negative electrodes respectively, hence the same metal can be both
positive and negative towards itself. In thermocells which convert heat into electricity,
with large temperature differences at the two junctions, the direction of the current is
reversed; the previously positive metal becomes negative and vice versa. Similarly,
there is no absolute series according to which the metals replace one another from their
chemical compounds
with a particular halogen or acid radicle; in many cases by supplying energy in the form of
heat we are able almost at will to alter and reverse the series valid for ordinary
temperatures.

Hence we find here a peculiar interaction between chemical action and electricity. The
chemical action in the battery, which provides the electricity with the total energy for
current formation, is in many cases first brought into operation, and in all cases
quantitatively regulated, by the electric charges developed in the battery. If previously the
processes in the battery seemed to be chemico-electric in nature, we see here that they are
just as much electro-chemical. From the point of view of formation of the constant
current, chemical action appears to be the primary thing: from the point of view of
excitation of current it appears as secondary and accessory. The reciprocal action
excludes any absolute primary or absolute secondary; but it is just as much a double-sided
process which from its very nature can be regarded from two different standpoints; to be
understood in its totality it must even be investigated from both standpoints one after the
other, before the total result can be arrived at. If, however, we adhere onesidedly to a
single standpoint as the absolute one in contrast to the other, or if we arbitrarily jump
from one to the other according to the momentary needs of our argument, we shall remain
entangled in the onesidedness of metaphysical thinking; the interconnection escapes us and we
become involved in one contradiction after another.

We saw above that, according to Wiedemann, the initial deflection of the galvanometer,
immediately after dipping the exciting plates into the liquid of the battery and before
chemical changes have altered the strength of the electric excitation, is "a measure of the
sum of electromotive forces in the circuit."

So far we have become acquainted with the so-called electromotive force as a form of
energy, which in our case was produced in an equivalent amount from chemical energy, and
which in the further course of the process became reconverted into equivalent quantities of
heat, mass motion, etc. Here we learn all at once that the "sum of the electromotive forces
in the circuit" is already in existence before this energy has been liberated by
chemical changes; in other words, that the electromotive force is nothing but the capacity of
a particular cell to liberate a particular quantity of chemical energy in unit time and to
convert it into electric motion. As previously in the case of the electric force of
separation, so here also the electromotive force appears as a force which does not contain a
single spark of energy. Consequently, Wiedemann understands by "electromotive force" two
totally different things: on the one hand, the capacity of a battery to liberate a definite
quantity of given chemical energy and to convert it into electric motion, on the other hand,
the quantity of electric motion itself that is developed. The fact that the two are
proportional, that the one is a measure for the other, does not do away with the distinction
between them. The chemical action in the battery, the quantity of electricity developed, and
the heat in the circuit derived from it, when no other work is performed, are even more than
proportional, they are equivalent; but that does not infringe the diversity between them. The
capacity of a steam engine with a given cylinder bore and piston stroke to produce a given
quantity of mechanical motion from the heat supplied is very different from this mechanical
motion itself, however proportional to it it may be. And while such a mode of speech was
tolerable at a time when natural science had not yet said anything of the conservation of
energy, nevertheless it is obvious that since the recognition of
this basic law it is no longer permissible to confuse real active energy in any form with the
capacity of an apparatus to impart this form to energy which is being liberated. This
confusion is a corollary of the confusion of force and energy in the case of the electric
force of separation; these two confusions provide a harmonious background for Wiedemann's
three mutually contradictory explanations of the current, and in the last resort are the
basis in general for all his errors and confusions in regard to so-called "electromotive
force."

Besides the above-considered peculiar interaction between chemical action and electricity
there is also a second point that they have in common which likewise indicates a closer
kinship between these two forms of motion. Both can exist only for an infinitesimal
period. The chemical process takes place suddenly for each group of atoms undergoing it. It
can be prolonged only by the presence of new material that continually renews it. The same
thing holds for electric motion. Hardly has it been produced from some other form of motion
before it is once more converted into a third form; only the continual readiness of available
energy can produce the constant current, in which at each moment new quantities of motion
assume the form of energy and lose it again.

An insight into this close connection of chemical and electric action and vice
versa will lead to important results in both spheres of investigation.[25] Such an insight is already becoming more
and more widespread. Among chemists, Lothar Meyer, and after him Kekulé, have plainly stated
that a revival of the electro-chemical
theory in a rejuvenated form is impending. Among electricians also, as indicated especially
by the latest works of F. Kohlrausch, the conviction seems finally to have taken hold that
only exact attention to the chemical processes in the battery and decomposition cell can help
their science to emerge from the blind alley of old traditions.

And in fact one cannot see how else a firm foundation is to be given to the theory of
galvanism and so secondarily to that of magnetism and static electricity, other than by a
chemically exact general revision of all traditional uncontrolled experiments made from an
obsolete scientific standpoint, with exact attention to establishing the energy changes and
preliminary rejection of all traditional theoretical notions about electricity.

Notes

1. For the factual material in this chapter we
rely mainly on Wiedemann's Lehre vom Galvanismus and Elektromagnetismus [Theory
of Galvanism and Electro-Magnetism], 2 vols. in 3 parts, 2nd edition, Braunschweig,
1874.

In Nature, June 15, 1882, there is a reference to this "admirable treatise,
which in its forthcoming shape, with electrostatics added, will be the greatest experimental
treatise on electricity in existence." [Note by F. Engels.]

2. The central discovery was J. J. Thomson's
discovery of the electron.

5. We now know that a current in metals is
due to a movement of electrons, whereas in electrolytes, e.g. salt water and gases, molecules
with both positive and negative charges carry it.

6. This is incorrect, but was generally
stated in textbooks at the time when Engels wrote.

7. The view that electrical energy was
located in the ether was the basis of the experiments which gave us radio. It seemed in turn
to have been negated by the discovery of electrons. However, the electron in turn is now
regarded by many physicists as a system of waves rather than a well-defined particle.

10. I use the term " electricity " in the
sense of electric motion with the same justification that the general term " heat " is used
to express the form of motion that our senses perceive as heat. This is the less open to
objection in as much as any possible confusion with the state of stress of electricity is
here expressly excluded in advance. [Note by F. Engels.]

11. Once more it must be remembered that
this term was very loosely used sixty years ago, and now has a definite meaning, not of
course equivalent to any form of energy.

14. F. Kohlrausch has recently calculated
(Wiedemann's Annalen, VI, p. 206) that "immense forces" are required to drive the
ions through the water solvent. To cause one milligram to move through a distance of one
millimetre requires an attractive force which for H ==32,500 kg., for Cl=5,200 kg., hence for
HCl=37,700 kg. - Even if these figures are absolutely correct, they do not affect what has
been said above. But the calculation contains the hypothetical factors hitherto inevitable in
the sphere of electricity and therefore requires control by experiment.[*] Such control appears possible. In the first place, these
"immense forces" must reappear as a definite quantity of energy in the place where they are
consumed, i.e. in the above case in the battery. Secondly, the energy consumed by
them must be smaller than that supplied by the chemical processes of the battery, and there
should be a definite difference. Thirdly, this difference must be used up in the rest of the
circuit and likewise be quantitatively demonstrable there. Only after confirmation by this
control can the above figures be regarded as final. The demonstration in the decomposition
cell appears still more susceptible of realisation. (Note by F. Engels.)

* Actually the hypothesis was incorrect. It
is now believed that when HCl is dissolved in water, it is almost completely broken up into
positive H ions and negative Cl ions, which do not require "immense forces" to drive them.
Engels was fully justified in his scepticism.

15. It may be noted here once for all that
Wiedemann employs throughout the old chemical equivalent values, writing HO, ZnCl, etc. In my
equations, the modern atomic weights are everywhere employed, putting, therefore,
H2O, ZnCl2, etc. [Note by F.
Engels.]

16. As it stands this is untrue. Probably
"part by weight" is a slip of Engels' pen for "equivalent by weight" or some such phrase.

17. Again this does not make sense as it
stands. Presumably Engels meant to refer to a hypothetical AuCl.

18. This quantity has now not only been
determined but utilised. Thus if the hydrogen is previously split into atoms, the ordinary
oxy-hydrogen flame can be made a great deal hotter.

20. This statement has been very fully
confirmed by the progress of physics in the last fifty years. It is interesting to note that
idealistic writers have used this disappearance of the notion of force as an argument that
materialism is being refuted!

21. In all the following data relating to
current strength, the Daniell cell is put==100. [Note by F. Engels.]

22. A column of the purest water prepared
by Kohlrausch 1mm. in length offered the same resistance as a copper conductor of the same
diameter and a length approximately that of the moon's orbit. Naumann, Allgemeine
Chemie [General Chemistry], p. 729.[**] [Note by F. Engels.]

23. This statement is in accord with theory
fifty years ago, but incorrect.

24. This is, of course, not electromotive
force in the modern sense of the term.

25. This has, of course, been very
completely verified by the researches of the last fifty years. Electrical theory was
revolutionised by Thomson's study of electrical conduction in gases, which led to his
discovery of electrons. And the whole of chemistry, including the chemistry of such unions
as that between carbon and hydrogen, which at first sight is quite unconnected with
electrical phenomena, has been restated in terms of electrons.